Digital display device

ABSTRACT

A digital display device includes an upper and lower row of electroluminescent display elements each controlled by a silicon controlled rectifier gated by the output of a stage of a data buffer for applying an alternating potential to each display element; a blanking control circuit for controlling the amplitude of the alternating potential applied to the display elements; an image control switch for selectively operating the display device to be unblanked, to be blanked or to be automatically blanked except when input lines are energized; and a display time extension circuit for allowing a display device to be operational for a period of time after the input lines are de-energized.

United States Patent Alexander Dec. 25, 1973 PULSE ANALYZING TESTERPrima Examiner-John W. Caldwell 75ItzAthl) AldRlh, men or aelg AssistantExaminer-Marshall M. Curtis Attorney-Ralph L. Thomas et al. [73]Assignee: International Business Machines Corporation, Armonk, N.Y. 57ABSTRACT [22] Filed: June 22, 1972 A digital display device includes anupper'and lower row of electroluminescent display elements each con-[211 Appl 266515 trolled by a silicon controlled rectifier gated by theRelated U.S. Application Data output of a stage of a data buffer forapplying an alter- [62] Division of Ser. No. 88,298, Nov. 11, 1970."fling Potential to each p y element; a blanking control circuit forcontrolling the amplitude of the al- [52] US. Cl. 340/324 M, 340/166 ELternating potential pp to the p y elements; an [51] Int. Cl G06g 7/04image Control Switch for Selectively operating the 58 Field of Search340/324 R, 324 M, p y device to be unblanked, to be blanked or to be340/166 EL automatically blanked except when input lines are energized;and a display time extension circuit for allow- [56] Reference Cit d inga display device to be operational for a period of UNITED STATES PATENTStime after the input lines are de-energized. 3,543,248 l1/l970 Oliver340/166 EL 3 Claims, 5 Drawing Figures HH PHOSPHOR 2 SEGMENT 2 TI'G'HTJPI E CONNECTING PIN.) k f 290VAC GLASS I \43 Q 400111 N TRANSPARENTELECTRODE i141 PATENTEB 3. 781 .851

A sum 3 nrs 852 PARALLEL OUTPUT DATA REGISTER XXIX! scR. SCR

; II L ,42 I 1 4 J um I: I9 20 7 I BLANK m4- n|5- CONTROL I l- H42 1 4l|34-\ n35 I93\ SCR scR L L 195 904 905 W l 9|o 1 PARALLEL 9|| OUTPUTDATA F|G 2b REGISTER llllllllH PULSE ANALYZING TESTER This is a divisionof application. Ser. No. 88,298, filed Nov. 11,1970.

BACKGROUND OF THE INVENTION two rows of a digital display with onesignal displayed in one row and the other signal displayed in the otherrow.

The foregoing and other objects, features and advantages of theinvention will be apparent from the follow- This invention relates todisplay devices and more ing more particular description of a preferredembodiparticularly to digital display devices having a number merit ofthe invention, as illustrated in the accompanyof discrete displayelements and including driving ciri n g d r awings. N g cuits toactivate each individual display element ac- BRIEF DESCRIPTION OF THEDRAWINGS cording to the input to each driving circuit. to

In the past digital display devices have most FI G. 1 illustrates inblock form a test instrument emmonly consisted of a number of individuallamp ele- Ploymg to this mvenuonments such as incandescent bulbs eachfor indicating SQ t zh 2B t f aglgltal d'splay deuce a cor ing 0 epresen inven ion. gi t or absence of a pattlcular b" m a data FIG. 3shows a section view of the digital display de- The prior art controlcircuitry does not permit selecvtce of t 2A tively blanked, unblanked orautomatically blanked i F 4 ts a schemattc t' t t showmg l 'f imagedisplay. Also, the prior art does not provide a g g tg the dtgttatdtsptay devtce S own m bright flicker-free data display.

DESCRIPTION OF THE PREFERRED SUMMARY OF THE INVENTION EMBODIMENTSTherefore, a digital display device according to the 1"" presentinvention includes a plurality of display elef P and descnpuon of thements arranged in rows wherein each element is activentlon 1Scompttedttom a more cttmptete descttptton vated by a gated power controldevice. Data is trans- Ofa sy.stem emtzfdymg t ptesent mtgntttsm gg gaferred from a data buffer to the gate of the power con- Kis ig mgappttcatton ttett trot devices to blank or unbtank respective t tReference is inade to FIG. 1 which illustrates in block element. Controllogic for controlling the application form the general System ofa testinstrument employing of the power source to the gated power controldevices to this invention A device under test 10 Supplies Permits thedisplay to be selectively blanked nals to amplitude discriminators 12through 15. Signals blanked, automatically blanked except when data fromthe amplitude discriminators 12 through 15 are input lines areactivesupplied through gating and control circuits 20 to an The controllogic also extends the time for a p y upper buffer 22 and a lower buffer24. Alternatively, device to be active for a duration after the datainput signals from the amplitude discriminators 12 through has beendeactivated to enable a brighter more flicker- 15 may be suppliedthrough the gating and control cirfree display. The display deviceincludes an upper row cuits 20 to the lower buffer 24 only. A ringcircuit 26 ofilluminable indicators and a lower row of illuminableoperates successively stages of the upper buffer 22 and indicators. Theilluminable indicators may be neon inthe lower buffer 24 to sample andstore signals from the dicator lamps, electroluminescent elements, lightemitamplituqe discriminators 12 through Thc Ting ting diodes, and thelike. The display device selectively t 26 operated by Oscluator TheOscillator may be operated (l) to be blanked at all times, to 28 1Sturned on and off in response to control signals be unblanked at alltimes, or (3) to be automatically the gatmg and Comm] clrcults dlsplayunblanked when incoming Signals are presented and vice 40 has an upperrow 42 of electrolum nescent eleautomatically blanked in the absence ofincoming sigments and a lower row of etectmtummescent nals. Visualindicators are provided to indicate to an g t tttfotmatton Stored m theupper may e displayed by the upper row 42 of electroluminescentopettttot the statutott the bttstc comm} devtces'. elements, andinformation stored in the lower buffer 24 It fefuure t l lnvfmnon topfovtde j test mstru' may be displayed in the lower row of 44 ofelectrolumiment with a digital display device which may be nescentelemenm blanked at all times, unblanked at all times, or automat- Animage comm] Switch 190 in F164 has a three l unblanked in response to anincoming Slgnal and sition lever, and various ones of the contacts 1through automatically blanked in the absence of an incoming 20 aregrounded by operating the [Wet Contact 4 is signal grounded as shown. Bya jumper arrangement is a feature of lrlVEntlOn to Provide for the CliS-grounded Contact is connected to contacts 6 7 9 10 play Of an incomingsignal in both lOWS ofa CllS- 15, and 19, Tab1e 1 below hows which onesof the play device which has two rows or to provide for the contacts aregrounded for the various positions of the display of two simultaneouslyincoming signals in the switch lever.

TABLE 1 L Contact numbers iisii t ion 123456789101112131416161718192o UpX X X X X X X X X X Center. X X X X X X X X X X Down.. X X X X X X X x XX l Contact 1 of the switch 190 is connected to an And circuit 191, andcontact is connected to an Or circuit 192. The Or circuit 192 isconnected to the And circuit 191. Output signals from the And circuit191 on a line 193 are used to control the blanking and unblanking of thedisplay device of 40 in FIG. 1. The image control switch 190 is a threeposition lever switch, and the three positions control the blanking,unblanking, and clearing of the display device 40 in FIG. 1. When theswitch lever is up, the display 40 in FIG. 1 is unblanked. When theimage control switch 190 in FIG. 4 is operated with its switch levercentered, it automatically clears the display device 40 in FIG. 1. Whenthe image control switch 190 in FIG. 4 is operated with its switch leverdown, it blanks the display device 40 in FIG. 1.

An Or circuit 194 in FIG. 4 is connected to an indicator lamp 195. Asingle shot 196 has its output connected to the Or circuits 192 and 194.Signals on the line 163 in are supplied through an inverter 197 to theOr circuit 194. The signals on a line 200 are supplied to the Orcircuits 192 and 194. The Or circuit 194 responds to a negative signalon any of its input lines and provides a negative output signal, asindicated by the half arrowhead on the output line at the junction withthis Or circuit,'which is effective to illuminate the lamp 195. The lamp195 is illuminated whenever the ring circuit 26 in FIG. 1 is operated.The Or circuit 192 responds to a negative signal on any one of its inputlines, as indicated by the half arrowhead at the junctions of theselines with this Or circuit, and supplies a positive output signal to theupper input of the And circuit 191.

Reference is made next to FIGS. 2A and 2B for a detailed illustration ofthe display element 40. The display element 40 has an upper displayregister 42 and a lower display register 44. The upper display register42 is composed of a plurality of phosphor segments 1101 through 1105.There are as many phosphor segments in each display register as thereare stages in the upper and lower buffers. However, only five phosphorsegmentsare shown, and they represent stages 1, 2, 3, 19 and 20.Phosphor segments 1101 through 1105 display information in therespective stages 1, 2, 3, 19, and 20 of the upper buffer. Phosphorelements for stages 4 through 18 of the upper buffer are not shown inthe interest of simplicity. The lower register 44 of the display device40 includes phosphor elements 1111 through 1115 which displayinformation stored in respective stages 1 through 3, 19, and 20 of thelower buffer 24. Phosphor elements for stages 4 through 18 of the lowerbuf e @430 netsbpw in the er of impl ci y- Signals from the upper buffer22 on the lines 801 through 805 are supplied to respective siliconcontrolled rectifiers 1121 through 1125. The silicon controlledrectifiers 1121 through 1125 are connected to respective phosphorelements 1101 through 1105. Signal s from the lower buffer 24 on lines901 through 905 are supplied to respective silicon controlled rectifiers1131 through 1135 which in turn are connected to corresponding phosphorelements 1111 through 1115. A source of alternating current 1141 in FIG.2B supplies an alternating potential on a line 1143 to the siliconcontrolled rectifiers 1121 through 1125 and 1131 through 1135. A blankcontrol 1142 responds to signals on the line 193 to control thealternating source 1141.

A positive signal on the line 193 operates the blank control 1142 toreduce the amplitude of the source 1141 thereby to deactivate thesilicon controlled rectifiers 1121 through 1125 and 1131 through 1135. Anegative signal on the line 193 operates the blank control 1142 toincrease the amplitude of the source 1141 thereby to condition thesilicon controlled rectifiers 1121 through 1125 and 1131 through 1135,and the silicon controlled rectifiers may then respond to signals fromthe upper and lower buffers. When the source 1141 is applied to the line1143, the silicon controlled rectifiers 1121 through 1125 respond topositive signals on corresponding lines 801 through 805 to illuminateassociated phosphor elements 1101 through 1105. When the source 1141 isapplied on the line 1143 to the silicon controlled rectifiers 1131through 1135. they respond to positive signals on respective lines 901through 905 to illuminate corresponding phosphor elements 1111 through1115. When the source 1141 is removed or its amplitude is decreasedsufficiently, the sil icon controlled rectifiers 1121 through 1125 and1131 through 1135 are deactivated, and the associated phosphor elements1101 through 1105 and 1111 through 1 are not illuminated by positivesignals on the associated lines 801 through 805 or the lines 901 through905.

Reference is made next to FIG. 3 which is a view taken on the line25A-25A in FIG. 2A showing phosphor elements 1101 and 1111 in crosssection, and associated circuit components are shown connectedtherewith. The silicon controlled rectifiers 1121 and 1131 are connectedthrough respective connecting pins 1150 and 1151 to associatedphosphorous elements or segments 1 101 and 111 1. These phosphoroussegments are attached to a transparent electrode 1152. The transparentelectrode 1152 is protected by a glass plate 1153. The source ofalternating current 1141 is connected between the transparent electrode1152 and the silicon controlled rectifiers 1121 and 1131. The blankcontrol 1142 in FIG. 2B is a silicon controlled rectifier 1149 andresistors 1154 and 1155 which form a series circuit. The resistor 1154is variable. The alternating current source 1141 is shunted by theseries circuit including the silicon controlled rectifier 1149 and theresistors 1154 and 1155. When a positive signal is supplied on the line193 to the silicon controlled rectifier 1149, this rectifier is turnedon, and most of the power from the source 1141 is dissipated in theresistors 1154 and 1155. This causes the silicon controlled rectifiers 1121 and 1131 to be deconditioned or turned off whereby the display 40 isblanked. When a negative signal is supplied on the line 193 to thesilicon controlled rectifier 1149, this rectifier is deconditioned orturned off, and the power from the source 1141 is applied to conditionthe silicon controls rectifiers 1121 and 1131. Ifa positive signal isapplied on the line 801 to the silicon controlled rectifier 1121, itthen conducts, and the signal from the source 1141 is supplied throughthe pin 1150 to the phosphor segment 1101. The signal across thisphosphor segment causes it to be illuminated, and light is projectedoutwardly from the face plate 1153. If a positive signal is applied onthe line 901, the silicon controlled rectifier 1131 is renderedconductive, and the signal from the source 1141 is applied across thephosphor segment 1111. This causes the phosphor segment 1111 to beilluminated and light is projected from the face plate 1153. Thus it isseen how the display device 40 in FIGS. 2A and 2B is operated in someinstances where it is not essential for an operator to view the displaydevice 40, a positive signal may be applied on the line 193 to blank thedisplay. This increases the useful life of the phosphorous segments.

The image control switch in FIG. 4 permits an operator to control thedisplay 40 in FIGS. 2A and 2B.

When the image control switch 190 is set to the stored (normal)position, the signals being displayed are retained until replaced bysignals in the next sweep. the ring circuit is not. With the imagecontrol switch 190 in FIG. 4 set to the auto cleared position, thedisplay is retained long enough to be seen and then is cleared. This isuseful during trouble analysis to prevent confusion as to whether adisplay is the result of one specific trial or is left over from aprevious trial. When the image control switch 190 is set to the blankedposition, no display is seen, but all other functions are carried out bythe test instrument in FIG. 1.

Since an oscilloscope and the test instrument in FIG. 1 display signalsfor analysis, a comparison of the two types of devices is appropriate.The oscilloscope creates a visible display with an electron gun whichdirects a stream of electrons against the inner face of a cathode raytube. This inner face is coated with a material which glows under suchbombardment and persists in glowing for a short time after thebombardment ceases. The point where the electrons strike the face of thecathode ray tube may be shifted in both the horizontal and verticalplanes by impressing voltages on the horizontal and vertical deflectionplates between the electrons flow. The horizontal plates are generallyconnected to a variable oscillator which causes the electron stream tosweep across the face of the cathode ray tube at a known rate and thenquickly fly back to begin another such sweep. The vertical "deflectionplates generally are connected to a signal source which causes thestream of electrons to shift vertically in proportion to the inputsignal voltage as the horizontal sweep takes place. This results in adisplayed line the shape of which represents the signal during a knownperiod of time. The device according to this invention does not utilizea cathode ray tube, electron gun, or deflection plates. It does,however, have a display face containing an upper and lower row ofsegments or phosphor elements as shown in FIG. 1. There are suchelements in each row, and each element represents a distinct timeinterval of the input signal. These elements are able to glow because ofelectroluminescence which is a property of emitting light when analternating current signal is applied. Very little heat is emitted byelectroluminescence. The light produced is roughly proportional to thevoltage and frequency of the excitation current. The excitation sourcemay be one which provides an alternating signal of 290 volts with afrequency of 400 cycles per second.

The device in FIG. 1 displays information in digital or binary formusing the two rows of phosphor elements in contrast to the analoguedisplay presented by an oscilloscope. The device in FIG. 1 takessuccessive samples of an input signal over a given time period, and thesignal during each time increment is sampled to determine whether or notit exceeds the clipping level of the associated amplitude discriminator.If the input signal during a given time increment exceeds the clippinglevel, the associated phosphor element is illuminated. Otherwise, theassociated phosphor element remains dark. This sampling action isdifferent from the horizontal sweep of an oscilloscope even though bothdevices generate a display. The device in FIG. 1 has a variable sweeprange, and the sweep may vary from 1.25 seconds per time increment to 50nanoseconds per time increment. The negative signal on the line 200 issupplied also to the Or circuit 192 which in turn provides a positiveoutput signal to the And circuit 191. Since the image control switch 190is set to the stored position, contact 1 is open, and this conditionsthe lower input of the And circuit Consequently, the And circuit 191responds to positive signals on its input lines and supplies a negativeoutput signal on the line 193 which operates the blank control 1142 inFIG. 28 to unblank the display 40 whereby signals stored in the upperand lower buffers may be visually displayed. It is pointed out that theimage control switch 190 provides a constant ground level from contact 5whenever this switch is placed in the stored position. Consequently, theground potential is effective to operate the Or circuit 192 to provide apositive output signal as long as this switch remains in the storedposition. This makes it unnecessary to utilize the negative outputsignal on the line 200 in this instance, but the negative signal on theline 200 is effective to unblank the display when ever the image controlswitch 190 is in the auto cleared position. The negative signal on theline 200 is supplied also to the Or circuit 194 in Flg. 4 which in turnsupplies a negative signal'from its output to the triggered lamp 195thereby to illuminate this lamp. Assume that the switch 190 in FIG. 4 isin the auto cleared position. When a sweep is initated as reflected bythe turning on of the ring start latch in the line 200 from the resetoutput of latch is presented to the lower leg of Or circuit 192. Theoutput of 192 is plus which is presented to And circuit 191. The outputof And 191 changes to a minus condition which unblanks display 40 aspreviously explained. For the same reasons previously described, a veryshort duration sweep, results in a very short time during which display40 is unblanked. This time could be extremely short and prevent operatorobservation of patterns occurring during the sweep. Referring now tosingle shot 196 shown in FIG. 4 it can be seen that the output of singleshot 196 is connected to the input of Or circuit 192. The center leg ofOr circuit 192 thus is changed to a minus condition at the completion ofthe sweep for the duration of single shot 196. This drives the output ofOr circuit 192 into its plus state which conditions the upper leg of Andcircuit 191. Thus, line 193 is in a minus condition for millisecondsfollowing the completion of the sweep. For the foregoing examples it wasassumed that the lower leg of And circuit 191 is in the plus conditionedstate. It has been previously shown that contact 1 of the image controlswitch is in the plus state when the switch is in the auto clearedposition. In review, the function of the single shot 196 primarily is toextend the duty cycle of display 40. This assures visual observation byan operator under all conditions. The worst case is that of fast sweepspeeds occurring only once or at a very low repetition rate.

While the invention has been particularly shown and described withreference to a preferred embodiment thereof, it will be understood bythose skilled in the art that the foregoing and other changes in formand details may be made therein without departing from the spirit andscope of the invention.

What is claimed is:

1. A digital display device having an upper row of display elements anda lower row of display elements,

a plurality of input lines for supplying signals to be displayed, aplurality of individual switch elements, said plurality of input linesbeing connected to said plurality of individual switch elements, saidplurala source of alternating current potential, first control meansconnected to said source of alternating potential for controlling themagnitude of the alternating current potential source applied to saiddisplay device, said source of alternating current potential beingsupplied to said individual switch elements, each individual switchelement responding to the alternating current signal and a signal on itsinput line to illuminate the associated display element, and

second control means, connected to said first control means, forselectively operating said display device to be unblanked at all times,to be blanked at all electroluminescent phosphorus element.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,7813251 Dated Dec. 25L 1973 Inventor) Arthur Duane ATexander It iscertified that: error appears in the above-identified patent and thatsaid Le'ttersPatent are hereby corrected as shown below:

- v I '1 r The Title reading "PULSE ANALYZING TESTER" should readDIGITAL DISPLAY DEVICE a Column 7, line 4, the word "applied" shouldread -supplied-,

Signed and sealed thia 16th day of July 197 (SEAL) Attest:

MCCOY M. GIBSON, JR. C. MARSHALL DANN Attesting Officer Commissioner of.Patents

1. A digital display device having an upper row of display elements anda lower row of display elements, a plurality of input lines forsupplying signals to be displayed, a plurality of individual switchelements, said plurality of input lines being connected to saidplurality of individual switch elements, said plurality of individualswitch elements being connected into the individual display elements ofthe upper and lower rows of display elements, a source of alternatingcurrent potential, first control means connected to said source ofalternating potential for controlling the magnitude of the alternatingcurrent potential source applied to said display device, said source ofalternating current potential being supplied to said individual switchelements, each individual switch element responding to the alternatingcurrent signal and a signal on its input line to illuminate theassociated display element, and second control means, connected to saidfirst control means, for selectively operating said display device to beunblanked at all times, to be blanked at all times, or to beautomatically blanked at all times except when said input lines areenergized.
 2. The device of claim 1 further comprising third controlmeans for extending the time of operation of the display device wheneverthe input lines are de-energized and the display is to be automaticallyblanked.
 3. A digital display device according to claim 1 wherein eachof said plurality of individual switch element comprises a gatedrectifier; and wherein each of said display elements comprises anelectroluminescent phosphorus element.